JPH11339833A - Fuel cell power generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of cells of a secondary battery connected to a fuel cell when load is high for optimum operation, efficiently charge the secondary battery, and enhance the efficiency as a system without increasing cost. SOLUTION: A hybrid fuel cell power generating system comprising a fuel cell 1 and a secondary battery 2 has a shutting off device 3 which connects cells 2a-2v whose output terminals are connected to the fuel cell 1 in parallel of the secondary battery 2 and the fuel cell 1 and shuts off the connection of them, and a control means 4 which controls the shutting off device 3 so that when current load is high, the number of cells of the secondary battery 2 connected to the fuel cell 1 is increased and when current load is low, the number of cells connected to the fuel cell 1 is decreased and the secondary battery 2 is charged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hybrid fuel cell power generator comprising a fuel cell and a secondary battery, wherein when the current load is large, the number of cells connected to the secondary battery is increased. When the current load is small, connecting and disconnecting the connection relationship between each cell of the secondary battery and the fuel cell so that the number of cells in the connection relationship of the secondary battery is reduced and the secondary battery is charged. The present invention relates to a fuel cell power generator for controlling a shutoff device.

[0002]

2. Description of the Related Art A fuel cell power generation system called a hybrid system using two types of batteries having different discharge characteristics, such as a fuel cell and a secondary battery such as a storage battery, is a quiet, non-polluting and highly efficient energy source. Source. However, due to the delay in gas supply, fuel cells cannot cope with the sudden increase in electric energy consumption. By using a secondary battery for that purpose, when the electrical energy is excessively necessary, the electrical energy is supplied from the secondary battery, and vice versa.
Using excess energy of fuel cell as charging energy 2
Store it in the next battery.

Conventionally, such a system has a DC converter DC connected between a fuel cell F and a secondary battery S as shown in FIG. 9 (JP-A-7-153474).
Also, some have a device that cuts off the power supply line of the fuel cell or the secondary battery when the current load is too high.

[0004]

However, when the conventional DC converter is connected, simply connecting the DC converter does not prevent a decrease in the terminal voltage of the fuel cell and also requires special control for the DC converter. Even when the means is added so that the terminal voltage of the fuel cell can be kept within a certain range, the output of the fuel cell is reduced by the decrease in efficiency due to the DC converter, and there is a problem that the cost increases. .

In the case of using the latter shut-off device, if the fuel cell is disconnected from the power supply line, the fuel cell cannot be used efficiently, and a plurality of shut-off devices are opened on the secondary battery side. Even when the voltage on the secondary battery side is lowered to make the charging current flow easily,
There is a problem that only the secondary battery is charged, and the amount of charge becomes unbalanced depending on the cells of the secondary battery.

Accordingly, the present inventor has proposed a hybrid fuel cell power generator comprising a fuel cell and a secondary battery,
When the current load is large, the number of cells connected to the secondary battery is increased, and when the current load is small, the number of cells connected to the secondary battery is reduced,
Focusing on the technical idea of the present invention of controlling a shut-off device for connecting and shutting off the connection relationship between each cell of the secondary battery and the fuel cell so that the secondary battery is charged, further research and development have been repeated. As a result, when the load is large, the purpose is to increase the number of cells connected to the secondary battery to achieve an optimal operation state, charge the secondary battery efficiently, and increase the efficiency of the system while suppressing cost increase. Achieved invention reached.

[0007]

According to a first aspect of the present invention, there is provided a fuel cell power generation apparatus comprising a fuel cell and a secondary battery. A shutoff device for connecting and shutting off the connection relationship between the cells of the battery and the fuel cell, and increasing the number of cells in the connection relationship of the secondary battery when the current load is large, and connecting the secondary battery when the current load is small. Control means for controlling the shut-off device so that the number of cells in a connection relationship is reduced and the secondary battery is charged.

According to a second aspect of the present invention, there is provided a fuel cell power generator according to the first aspect, wherein an output terminal of the shutoff device is connected in parallel to the fuel cell. .

The fuel cell power generator according to the present invention (third invention according to claim 3) according to the second invention, further comprises detecting means for detecting the voltage of the fuel cell and each voltage of the secondary battery. A fuel cell power generator characterized by the above-mentioned. Things.

[0010] In the fuel cell power generator according to the present invention (fourth aspect of the present invention), in the third aspect, the control means may be configured to determine the voltage of the fuel cell and the respective voltages of the secondary battery. It is configured to determine the magnitude of the current load.

In the fuel cell power generator according to the present invention (fifth invention according to claim 5), in the fourth invention, switch elements are respectively connected to both ends of each series-connected cell of the secondary battery. The control means is configured to control a connection relation of the switch elements according to a magnitude of a current load.

[0012] In the fuel cell power generator according to the present invention (a sixth invention according to a sixth aspect), in the fourth invention, a plurality of series-connected cell groups of the secondary battery are connected in parallel with each other, A switch element is provided at one end of each cell group, and the control means controls a connection relationship of the switch elements provided at one end of each cell group in accordance with a current load, thereby enabling the secondary battery to be connected. It is configured to control the number of cells in a connection relationship.

[0013]

In the fuel cell power generator according to the first aspect of the present invention, the control means increases the number of cells connected to the secondary battery when the current load is large, and reduces the current load. When the battery is small, the shut-off device for connecting and shutting off the connection of the cell of the secondary battery with the fuel cell so that the number of cells connected to the secondary battery is reduced and the secondary battery is charged. Control,
Enables the supply of electrical input / output corresponding to the current load,
This has the effect of suppressing high costs and increasing the efficiency of the system.

[0014] In the fuel cell power generator according to the second aspect of the present invention, the output terminal of the shut-off device is connected in parallel to the fuel cell in the first aspect of the invention. There is an effect that input / output can be supplied.

In the fuel cell power generator according to the third aspect of the present invention, the detecting means detects the voltage of the fuel cell and each voltage of the secondary battery in the second aspect of the invention, so that the detection means is adapted to the current load. This has the effect of enabling the supply of electrical input and output.

In the fuel cell power generator according to a fourth aspect of the present invention, the control means according to the third aspect, wherein the control means determines the magnitude of the current load from the detected voltage of the fuel cell and each voltage of the secondary battery. Since the determination is made, there is an effect that it is possible to supply the electrical input / output according to the current load or based on the constant current load.

According to a fifth aspect of the present invention, in the fuel cell power generator according to the fourth aspect of the present invention, the control means may control each of the series-connected cells of the secondary battery in accordance with a magnitude of a current load. Since the connection relation of the switch elements connected to both ends is controlled, an effect of realizing the supply of the electric input / output according to the current load is achieved.

The fuel cell power generator according to a sixth aspect of the present invention is the fuel cell power generator according to the fourth aspect, wherein the control means is connected in series with the secondary batteries corresponding to a current load and connected in parallel with each other. By controlling the connection relation of the switch elements disposed at one end of the group, the number of cells in the connection relation of the secondary battery is controlled, so that the supply of electric input / output based on a constant current load is performed. This has the effect of realizing it.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are described below.
This will be described with reference to the drawings.

(First Embodiment) A fuel cell power generator according to a first embodiment is an output terminal of a hybrid fuel cell power generator including a fuel cell 1 and a secondary battery 2 as shown in FIG. Are connected in parallel to the fuel cell 1 and connect and disconnect the cells 2a to 2v of the rechargeable battery 2 to and from the fuel cell 1, and the rechargeable battery 2 when the current load is large. Control the shut-off device 3 so as to charge the secondary battery 2 by reducing the number of cells in the connection relationship with the secondary battery 2 when the current load is small while increasing the number of cells in the connection relationship. And control means 4 for performing the operation.

The fuel cell power generator according to the first embodiment includes the fuel cell 1, the secondary battery 2 and a plurality of shut-off devices 3 or shut-off devices 3 having a multi-channel function. This is a fuel cell power generator in which a cell terminal is connected to the shutoff device 3 and an output terminal of the shutoff device 3 is connected in parallel to the fuel cell 1.

In the first embodiment, a voltage sensor which constitutes a detecting means for detecting the voltage of the fuel cell and each voltage of the secondary battery is provided, and the voltage of the fuel cell 1 and each voltage of the secondary battery 2 are provided. Each is configured to detect a voltage.

The control means 4 is configured to determine the magnitude of the current load from the detected voltage of the fuel cell 1 and each voltage of the secondary battery 2, and is connected in series with the secondary battery 2. Each of the switch elements 3a to 3w of the shutoff device 3 is connected to both ends of each of the cells, and the control means 4 is configured to control the connection relation of the switch elements according to the magnitude of the current load. Is what it is.

That is, the voltage of the fuel cell 1 and each voltage of the secondary battery 2 are detected, and when the current load is large, the number of cells of the secondary battery 2 is increased so as to cope with the load. When the current load is small, the number of cells of the secondary battery is reduced, and the multi-channel interrupting device 3 or the plurality of interrupting devices 3 is controlled so that the charging current to the secondary battery 2 flows more. That is, means 4 is provided.

As shown in FIG. 1, the fuel cell 1 is constituted by a fuel cell 1 of an alkaline type, a solid polymer type or the like, and an output terminal of the fuel cell 1 and each cell of a rechargeable secondary battery. The multi-channel cutoff device 3 is connected to terminals 2a to 2v.

An output terminal of the multi-channel cutoff device 3 is connected in series to a terminal of a current load 5 constituted by an electric motor or the like. The block constituting the control means 4 is connected in parallel to the output terminal of the fuel cell 1 and the secondary battery building block 2.

A control block constituting the control means 4 controls the multi-channel cut-off device 3 according to the first embodiment, and supplies hydrogen to the generally known fuel cell 1 and measures the temperature. It performs control and the like.

In the fuel cell power generator according to the first embodiment having the above-described configuration, when the current load of the hybrid system is equal to or more than a predetermined value, the control means 4 switches each switch element of the multi-channel cutoff device 3 to switch the switch. When more cells of the secondary battery 2 are connected, and when the value is equal to or less than a predetermined value, switching of the shutoff device 3 causes a smaller number of cells to be connected.
The secondary battery 2 is connected to the cell.

In this case, each cell 2a-2 of the secondary battery 2
The multi-channel cutoff device 3 allows a charging current to flow to any of the cells 2a to 2v of the secondary battery 2 so as to be charged in a well-balanced manner based on information from a voltage sensor connected to v.

At the time of starting, the multi-channel cutoff device 3
Thus, the load is connected so that the secondary battery 2 has the maximum number of cells. At this time, the fuel cell 1 is connected to the load 5
Is not connected, and the warm-up operation is being performed. When the fuel cell 1 is stabilized, it is connected to the load 5 for the first time.

Thereafter, when the load is small such as in an idling state, the number of cells of the secondary battery 2 connected to the load 5 is reduced by the multi-channel cutoff device 3 so that the fuel cell 1 , The voltage of the secondary battery 2 becomes lower, and a large charging current flows through the secondary battery discharged in large quantities at the time of starting or the like.

At this time, information of the secondary battery voltage sensor connected to each cell of the secondary battery 2 is taken into the control block 4 to calculate which cell is to be charged.

The charge / discharge control operation in the first embodiment will be described in detail with reference to FIGS. As shown in FIG. 3, the number of cells of the secondary battery 2 is (1),
A description will be given of a case of switching to the three stages (2) and (3).

[0034] At time 0 to time t ₁ as shown in FIG. 2 (a), the vehicle is stopped, but because in order to power the FC A ₁ kw necessary, brought out A ₁ kw from FC . Since the required power is small, the number of cells of the secondary battery 2 is controlled so as to obtain the characteristic (3).

The secondary battery 2 is charged by the difference between FC and the characteristic of (3). Therefore, the battery is charged more by the difference between the oblique line and the thick solid line shown in FIG.

From time t _{1 to} time t ₃ , since the vehicle is accelerating, the number of cells of the secondary battery 2 is switched so as to become (1). This mode is not different from the conventional system in which the number of cells of the secondary battery 2 is not particularly controlled.

[0037] At time t ₃ to time t _4, a constant-speed running condition, since the power required is reduced, only the hatched and dotted difference shown in FIG. 2 (c) switched as (2) conventional It can charge more than the system.

From the time t _{4 to the} time t ₅ , the vehicle is in the deceleration mode, and as in the case of the constant speed traveling mode, the battery can be charged by the difference between the hatched and dotted lines shown in FIG. 2C.

[0039] At time t ₅ to time t ₆ is the stop mode, switched as for the idle state (3). The battery can be charged more by the difference between the oblique line and the thick solid line shown in FIG.

The control flow in the first embodiment is shown in FIG.

The fuel cell power generation device according to the first embodiment having the above-described operation efficiently charges the secondary battery as described above, and is optimal for the connected secondary battery 2 when the load is large. To make sure that
This has the effect of increasing the efficiency of the system.

The fuel cell power generator according to the first embodiment can maintain an output voltage of the fuel cell 1 at a certain value or more even when a large current load is required, and can connect an efficient operation state. In addition, at the time of a small current load, the above-described method can efficiently charge the secondary battery 2, and thus has an effect of increasing the efficiency of the system.

(Second Embodiment) In the fuel cell power generator of the second embodiment, as shown in FIG. 5, the control means 4 in the first embodiment is focused on the charging efficiency of the secondary battery. Further, the present invention relates to a simplified fuel cell power generation system hybrid system aiming at lower cost and simpler control.

In the fuel cell power generator according to the second embodiment, as shown in FIG. 5, a plurality of cell groups connected in series of the secondary battery 2 are connected in parallel with each other, and one end of each cell group is connected to one end of each cell group. A switch element of the shutoff device 3 is provided, and the control means 4 controls a connection relationship of the switch element provided at one end of each cell group in accordance with a current load, thereby connecting the secondary battery. It is configured to control the number of related cells.

That is, as shown in FIG. 5, the output terminal of the secondary battery 2 and the output terminal of the fuel cell 1 are connected in parallel, and the second terminal for dividing the cells of the secondary battery into two halves.
Switch element 32 and the first and second switch elements 31, 32 of the shut-off device for connecting the respective secondary battery blocks (cell groups 2a to 2j, 2k to 2v) 21, 22 in parallel. It is a control system.

When the load is large, the first switch element 31 is opened and the second switch element 32 is connected to the secondary battery block 2K, so that all of the secondary batteries 2 are connected in series. To increase the output. Conversely, when the load is small, the first switch element 31 is connected to charge the secondary battery, and the second switch element 32
Is connected to the 2v side, the voltage of the secondary battery 2 becomes 1/2.

The charge / discharge control operation according to the second embodiment will be described in detail with reference to FIGS. 2, 3, 6, and 7. In the second embodiment, a case where the number of cells of the secondary battery 2 is switched between two stages (1) or (3) as shown in FIGS. 2 (e) and 3 will be described.

As shown in FIG. 2A, from time 0 to time t ₁ , the vehicle is in the stop mode, and the vehicle is in the idling state.
Since only half the cells of the secondary battery 2 are connected, and the characteristics shown in (3) are obtained, the battery is charged more by the difference between the oblique line and the thick solid line shown in FIG. 2C.

From time t _{1 to} time t ₃ , the vehicle is in the acceleration mode, and the maximum power is required.
All the cells of the secondary battery 2 are connected so as to have the characteristic (1), and the charging efficiency is the same as that of the conventional system.

From time t _{3 to} time t ₄ , the vehicle is traveling at a constant speed and only two stages are switched. In this mode, all the cells of the secondary battery 2 are connected.
The charging efficiency is the same as the conventional system.

From time t _{4 to} time t ₅ , the mode is the deceleration mode, and only two stages are switched. In this mode, all the cells of the secondary battery 2 are connected, and the charging efficiency of the conventional system is lower than that of the conventional system. does not change.

From time t _{5 to} time t ₆ , the mode is the stop mode, and the system is switched to the idle mode as shown in (3). The battery can be charged more by the difference between the oblique line and the thick solid line shown in FIG.

The control flow in the second embodiment is shown in FIG.

In the fuel cell power generator according to the second embodiment having the above-described operation, the control means 4 is connected to one end of a cell group connected in series with the secondary batteries 2 in parallel with each other in response to a current load. By controlling the connection relationship of the switch elements disposed in the battery cell, the number of cells in the connection relationship of the secondary battery is controlled, thereby realizing the supply of electrical input / output based on a constant current load. As a result, a large charging current flows to the secondary battery 2, which has an effect that charging can be performed efficiently.

The fuel cell power generator according to the second embodiment
By controlling the control means 4 to the charging efficiency of the secondary battery, it is possible to achieve a simpler control at a lower cost.

The above-described embodiments are exemplarily described for explanation, and the present invention is not limited to these embodiments. Those skilled in the art will recognize from the claims, the detailed description of the invention, and the drawings. Modifications and additions are possible without departing from the technical idea of the present invention.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a fuel cell power generator according to a first embodiment of the present invention.

FIG. 2 is a time chart showing waveforms at various points in the fuel cell power generator according to the first and second embodiments.

FIG. 3 is a diagram showing current-voltage characteristics in the first embodiment.

FIG. 4 is a chart showing a control flow in the first embodiment.

FIG. 5 is a block diagram showing a fuel cell power generator according to a second embodiment of the present invention.

FIG. 6 is a diagram showing current-voltage characteristics in the second embodiment.

FIG. 7 is a diagram showing control at the time of a load change in the second embodiment.

FIG. 8 is a chart showing a control flow according to the second embodiment.

FIG. 9 is a block diagram showing a conventional fuel cell power generator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Secondary battery 2a-2v cell 3 Interruption device 4 Control means

Claims (6)

[Claims] 1. A hybrid fuel cell power generator comprising a fuel cell and a secondary battery, comprising: a disconnecting device for connecting and disconnecting a connection relationship between cells of the secondary battery to the fuel cell; The number of cells in the connection relationship of the secondary battery is increased, and when the current load is small, the number of cells in the connection relationship of the secondary battery is reduced to charge the secondary battery. Control means for controlling the shut-off device. 2. The fuel cell power generator according to claim 1, wherein an output terminal of the shutoff device is connected in parallel with the fuel cell. 3. The fuel cell power generator according to claim 2, further comprising a detecting unit that detects a voltage of the fuel cell and each voltage of the secondary battery. 4. The fuel cell system according to claim 3, wherein the control means is configured to determine the magnitude of the current load from the detected voltage of the fuel cell and each voltage of the secondary battery. Fuel cell power generator. 5. The switch according to claim 4, wherein a switch element is connected to both ends of each of the cells connected in series of the secondary battery, and wherein the control means connects the switch element according to a magnitude of a current load. A fuel cell power generator, wherein the relation is controlled. 6. The cell according to claim 4, wherein a plurality of cell groups connected in series of the secondary battery are connected in parallel with each other, and a switch element is provided at one end of each cell group. By controlling the connection relationship of the switch elements disposed at one end of each cell group corresponding to the load, the number of cells in the connection relationship of the secondary batteries is controlled. Fuel cell power plant.